For part (a), we know that 6/60 pupils wear glasses. We also know that there are 360 degrees in the pie chart. So the angles for people who wear glasses must be (6/60)*360. 6/60 simplifies to 1/10, and a tenth of 360 equals 36. So the angle must be 36 degrees. To find the other angle, simply subtract 36 from 360 degrees to get 324 degrees.
For part (b), it is not possible to tell because all 6 pupils who wear glasses could be girls, they could all be boys, some girls and some boys, etc. We cannot know which one it is, given only that much information.
Hope this helps!